Как добавить свойство в объект?

populateData: function(data, coords) {
            var startPoint = new google.maps.LatLng(coords.lat, coords.long);
            var items = [];
            for (i = 0; i < data.length; i++) {
                var eventCoords = data[i].coords.split(', ');
                var endPoint = new google.maps.LatLng(eventCoords[0], eventCoords[1]);
                var distance = ((google.maps.geometry.spherical.computeDistanceBetween(startPoint, endPoint))/1000).toFixed(1)+' км';
                data[i].distance = distance;
                console.log(data[i].distance); // undefined!
                items.push(data[i]);
            }
            return items;
        },